1. Field of the Development
This application relates generally to conveyor systems for transporting objects, and more specifically refers to methods and devices for dissipating forces in conveyor joints.
2. Description of the Related Art and Problem to be Solved
Conveyor systems are useful in selecting, sorting, and transporting objects from one location to another. A conveyor system may be made up of individual conveyor units, or “carriers,” which are connected together by joints to make up a conveyor train. The conveyor train typically rides on a track in a continuous loop. An individual carrier may be equipped with a discharge device such as a motor-driven cross-belt, a tilt-tray, or a diverter paddle, etc. for discharging objects carried atop the carrier in a direction transverse to the direction traveled by the conveyor train. The discharge device is programmed to activate at a pre-programmed time and location along the conveyor track based on, for example, the characteristics of the object being transported.
A conveyor system may be employed in package sorting facilities, and as such will often travel a circuitous route through the facility, receiving and distributing packages at multiple locations. In the process, a conveyor system may be required to travel through multiple curves of varying radii and additionally travel up and down inclines of varying elevations. Non-linear travel in a conveyor system creates difficulty in establishing and maintaining a constant speed for the conveyor train. As a result, the non-linear travel may also cause timing irregularities for the discharge devices in discharging the objects being carried.
Also, conveyor systems with curved tracks and elevation changes tend to experience significant mechanical failure at a higher frequency than do conveyor systems with straight tracks alone. Such mechanical failure necessitates the need for frequent stoppage of the system for maintenance and repair. The joints connecting the conveyor carriers are particularly vulnerable to flexural fatigue in non-linear conveyor systems. The joints provide a point of connection between the conveyor carriers and thus facilitate turning of the conveyor train through the curves. Much of the axial forces experienced by the conveyor system are, thus, focused on the joints. The axial forces may cause flexural fatigue in the joints, leading to deterioration of the structural integrity of the metal joint components. When the joints deteriorate, many of the joint components may become loose or fit poorly together and require frequent repair. Joint deterioration may also cause the joint components to repeatedly collide together, causing high-decibel noise levels unsuitable for workers attending the conveyor system.
An inability of the joints to absorb the axial forces experienced in a non-linear conveyor system leads not only to break down of the joints themselves, but to transmission of the axial forces from the joints into the frame of the conveyor system. The transmitted forces may cause damage to the track and conveyor system support structure. In this manner, a non-linear conveyor system has historically required longer and more frequent maintenance stoppage time, resulting in costly repairs to the conveyor track and conveyor carriers, not to mention the opportunity cost of not being able to run the conveyor system as long as one would ideally like.
Previous attempts at mitigating the forces exhibited in non-linear conveyor systems have included the use of slip joints disposed between conveyor carriers at periodic locations along the carrier train. For practical reasons, the slip joints cannot be used between each individual conveyor carrier without causing slack to build up in the conveyor train. Thus, the forces experienced by the majority of individual joints connecting the conveyor carriers are not dissipated even with the use of slip joints.
Another attempt at mitigating the forces in non-linear conveyor systems has included the use of ball joints to connect the conveyor carriers. Often Teflon or other coating materials have been placed over the ball of the ball joint or on the inside of the housing to protect the joint from frictional forces that the joint experiences in a non-linear conveyor system. The use of a ball joint has proven inadequate, however, in dealing with the forces experienced in the non-linear conveyor system because the ball joint is unable to dissipate the axial forces experienced by the joint. The Teflon coating simply acts as a small buffer between the housing and ball portions of the ball joint to prevent wear on the ball. The joint is unable to dissipate and control the axial forces experienced by the joint in a curve in a non-linear conveyor system. The coating material is liable to wear out quickly and need frequent replacement. Furthermore, the axial forces experienced by the joints are still transferred to the overall conveyor system, leading to system damage and potential timing irregularities.